Near-infrared time-resolved optical absorption studies of the reaction of fully reduced cytochrome c oxidase with dioxygen.
Near-infrared time-resolved optical absorption studies of the reaction of fully reduced cytochrome c oxidase with dioxygen.
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DOI：
10.1021/bi002220v
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发表时间：
2001-01
期刊：
影响因子：
2.9
通讯作者：
I. Szundi;Guang-Ling Liao;Ó. Einarsdóttir
中科院分区：
文献类型：
--
作者：
I. Szundi;Guang-Ling Liao;Ó. Einarsdóttir
在24 ℃下，在近红外区域的完全还原的CO-结合复合物的光解后，已研究了完全还原的牛心细胞色素氧化酶与分子氧反应过程中的电子转移。瞬态光谱的变化和动力学微秒到毫秒的时间尺度上，在597和935 nm之间的9个不同的波长，并进行了分析，使用奇异值分解和全球指数拟合。四个表观寿命，14微米，40微米，86微米，和1.1毫秒，解决了。根据先前提出的机理[Sucheta et al.（1998）Biochemistry 37，17905-17914]提取中间体的近红外光谱，并与假定中间体的模型光谱进行比较。这些数据提供了不同氧化还原中心在近红外区域中各自氧化或连接状态下的光谱贡献的全面图片，并强烈支持Cu（A）在3-电子还原的铁基中间体中部分（2/3）氧化，但不完全氧化。
Electron transfer during the reaction of fully reduced bovine heart cytochrome oxidase with dioxygen has been studied at 24 degrees C in the near-infrared region following photolysis of the fully reduced CO-bound complex. The transient spectral changes and kinetics were followed on microsecond to millisecond time scales at nine different wavelengths between 597 and 935 nm and were analyzed using singular value decomposition and global exponential fitting. Four apparent lifetimes, 14 micros, 40 micros, 86 micros, and 1.1 ms, were resolved. The near-infrared spectra of the intermediates are extracted on the basis of a previously proposed mechanism [Sucheta et al. (1998) Biochemistry 37, 17905-17914] and compared to model spectra of the postulated intermediates. The data provide a comprehensive picture of the spectral contributions of the different redox centers in their respective oxidation or ligation states in the near-infrared region and strongly support that Cu(A) is partially (2/3), but not fully, oxidized in the 3-electron-reduced ferryl intermediate.